RFR: 8292739: Invalid legacy entries may be returned by Provider.getServices() call

[Valerie Peng]

Invalid legacy services are screened and removed in Provider.getService(...) call. This fix is to also screen and remove the invalid legacy services when Provider.getServices() is called.

Leveraged existing test case to test this particular scenario by adding one invalid legacy registration.

Thanks!
Valerie

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Commit messages:
 - 8292739: Invalid legacy entries may be returned by Provider.getServices() call

Changes: https://git.openjdk.org/jdk/pull/9992/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9992&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292739
  Stats: 19 lines in 2 files changed: 15 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/9992.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9992/head:pull/9992

PR: https://git.openjdk.org/jdk/pull/9992